Three-positions sliding gate valve

ABSTRACT

The present invention has for its object a discharge gate for a container holding liquid metal, comprising two refractory members which are in face-to-face contact and are slidable one with respect to the other to open and close the gate, each of the members having a central aperture, which apertures are in register when the gate is open, and the gate being arranged such that the members can be moved with respect to one another in two, opposite directions away from the open position, for closing the gate, the gate thereby having two, different closed positions.

BACKGROUND OF THE INVENTION

Sliding discharge gate in conceptions have been known in their generalprinciples for several decades, but in recent years they haveprogressively begun to substitute rod-type gates.

The principal advantages of sliding discharge gates with respect torod-type gates consists essentially in the fact that the refractorieswhich form the obturator last longer, as well as the fact that they canbe exchanged from outside the ladle without waiting to cool the ladle toallow access of workmen to its interior. However, also in slidingdischarge gates of known type there are some inconveniences:

First of all, it is not always easy to replace the refractory elementswhich must attend to the discharger sealing.

Secondly, said refractory material elements may break on account of thethermal variations which they undergo.

Thirdly, it is not easy to control the relative position of the slidingdischarge gate during its operations.

Finally, it happens in known devices that the discharge gate opening andclosing movement causes irregular wear to the various parts ofrefractory material elements, so that said elements must be replacedafter comparatively short operation periods.

OBJECT OF THE INVENTION

The invention has for its object an improved sliding discharge gate,characterised in that it has one opening position and two closingpositions, so as to obtain uniform wear of the refractory materialelements, and hence a longer life of same.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a transverse section of the sliding discharge gate accordingto the invention, i.e. a section perpendicular to the direction ofmovement of the obturator;

FIG. 2 is a vertical longitudinal section of the same gate, i.e. avertical section parallel to the direction of movement of the obturator;it will be noted that this Figure shows a partial section and does notinclude the means for actuating the obturator, which are shown in thefollowing

FIG. 3 which forms the natural extension to the right of FIG. 2;

FIG. 4 is a section along the plane IV--IV of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT

With particular reference to the Figures listed above, in a way knownper se, the sliding discharge gate comprises a fixed, upper metallicplate 10 fixed to the base 20 of the ladle and provided with a centralaperture which receives the lower end of a refractory sleeve 21 whichtapers in a upwards direction in such a manner that it can be exchangedfrom outside the ladle.

There is a rectangular projection 11 on the lower face of the upperfixed plate 10, defining a cuboidal space in which is received a fixed,upper refractory brick 12 provided with a central aperture 13registering with the aperture 22 in the sleeve 21. Four lugs 14 areprovided at the four corners of the upper, fixed plate 10, projectingdownwards, with the lower parts of the lugs 14 providingvertically-elongated eyes 15 suitable for receiving, with vertical play,pins 31 of a lower support plate 30 whose vertical position can beadjusted in the way described below but which is fixed to the upper,fixed plate 10 in respect of movements in the horizontal plane.

Thus, the lower support plate 30 is suspended from the upper fixed plate10 by means of the lugs 14.

The lower support plate 30 is provided, as can be seen in FIG. 1, withsliding guides 32 for longitudinal edges of an intermediate slidingplate 40 whose upper face provides a cuboidal seat for an aperturedrefractory brick 41 which can slide longitudinally together with theplate 40. The brick 41 has an aperture 42 in a position which is centralboth longitudinally and traversely and which, when it registers with theaperture 13, determines the open position of the fate. When saidaperture 42 is not in register with the aperture 13, the gate is in aclosed position and the seal is formed by the correct contact of thefacing surfaces of the two refractory bricks 12 and 41.

For this purpose, the lower support plate 30 is provided with alongitudinal flange 33 below which, according to a previous invention ofthe same Applicant, run wedges 61,63 which allow the support plate 30 tobe raised if the facing surfaces of the two bricks 12 and 41 are notperfectly coplanar and in contact with one another. In such a position,which is the position illustrated in FIG. 1, the pin 31 received in theeyes 15 no longer support the lower support plate 30, but said wedges doso.

These latter are in turn supported by U-shaped duides 50 which arerotatably supported by pivots 53 fixed on the upper plate 10, whichpermit the U-shaped guides 50 to swing outwards in accordance with thedirection indicated by the arrows 52, when said U-shaped guides areswung outwards to allow the gate to be dismounted, the support plate 30is once again supported directly by means of the pins 31.

Because, according to the invention, the aperture 42 in the refractorybrick 41 is in a central position, the seal of the sliding dischargegate can be obtained whether displacing the sliding plate 40 towards theleft, as seen in FIG. 2, until the aperture 42 in the refractory brick41 occupies the position 142 indicated by the - dot lines, or towardsthe right until the aperture 42 occupies the position 242 also indicatedwith-dot lines in FIG. 2.

In consequence, both the left-hand side upper surface of the brick 41and the right-hand side surface of the same are used as sealingsurfaces.

In order to move the sliding plate 30 and the brick 41 which is fixedthereto, one uses an actuating rod 51 whose end, see FIG. 3, has aconnection piece 52 in which is fixed the end of a piston rod 54 of theram 56.

The connection piece 52 is guided in a guide sleeve 55 fixed to thesupport plate 30 and whose end also supports the ram 56.

In FIG. 3, the connection piece 52 is in a position corresponding to theposition 42 of the aperture in the brick 41; hence, when the connectionpiece 42 occupies the position illustrated in FIG. 3, the discharge gateis open. In order to move the discharge gate into the closed position inwhich the aperture 42 in the brick 41 occupies the position 142, it isnecessary to move the connection piece 52 into the position 152 by meansof the double acting ram 56; correspondingly, in order to move theaperture in the refractory brick 41 into the closed position 242, it isnecessary to move the connection piece 52 into the position 252.

It is evident that if one wants to use the right-hand portion of theupper face of the brick 41 as the sealing surface, the aperture in thebrick 42 must be moved from the position 42 into the position 142 andvice versa; correspondingly the connecting piece will be movedalternatively between the positions 52 and 152.

If one instead wants to use the left portion of the upper face of thebrick 41 as sealing surface, the connection piece will be movedalternatively between the positions 52 and 252.

Correspondingly the aperture in the brick will be moved between thepositions 42 and 242.

In the two cases the movement of the connection piece will be the sameamount but in different directions as indicated by S1 and S2 in FIG. 3.

The extreme left-hand side of the movement S1 is defined by suitableshoulders on the guide sleeve 55; the same occurs for the extreme rightof the movement S2. On the other hand, in order to find the extremeright-hand or the extreme left-hand, of the movement S1 or S2, accordingto the invention, an abutment fork is provided, insertable transverselyinto the sleeve 45 alternatively in the position 157 and 257.

Such an abutment fork is insertable laterally through suitable openingsprovided in the walls of the guide sleeve 55.

In such a manner, it is possible to double the life of the refractorybricks and hence the interval between dismantling the sliding dischargegate and dismantling in the next time.

With particular reference to FIG. 4, this Figure shows a particularlyuseful variant of the wedges for the correct height position of thesupport plate 30.

According to the invention, two wedges 61 are symmetrically positionedin each of the U-shaped guides 50 in contact with the bottom of theguide, with the bottoms of the wedges horizontal and the upper faces 62inclined in opposite directions. On said inclined faces 62 rest theopposed and inclined faces of an upper double wedge 63 whose planarupper face supports the flange 33 of the support plate 30. The twolonger wedges 61 approach one another and move away from one another atthe same time because of a single threaded spindle 64 actuated by acontrol head 65; the said spindle is subdivided in two portions one ofwhich is left-handed and the other right-handed. In this way, when thespindle is rotated in one sense, the two lower wedges 61 approach oneanother and the upper double wedge is raised; when said spindle isrotated in the opposite sense, the two lower wedges 61 move apart andthe upper double wedge is lowered.

Although, for the sake of description, the present invention has beenbased on that described above and illustrated only by way of examplewith particular reference to the attached drawings, many modificationsand variants can be introduced into the realization of the discovery,and if such modifications and variants must be all the same consideredto be based on the claims which follow.

What we claim is:
 1. Improved sliding discharge gate, of the type whichcomprises an upper, fixed plate firmly connected to the base of theladle, a lower support plate supported, in such a way that its heightcan be adjusted, from the upper plate and an intermediate plate which isslidable by suitable actuating means, in which the upper, fixed plateand the slidable intermediate plate are apertured and are each connectedto a respective apertured refractory brick, in which in addition saidlower support plate provides a pair of guides on which the longitudinaledges of the intermediate slidable plate slide, characterised by thefact that the apertures in the two said apertured bricks are disposed ina position which is central both relative to their longitudinaldirection and relative to their transverse direction, in such a waythat, from an open position of the gate in which the apertures in thetwo bricks are in register, two symmetrical closed position can bereached.
 2. Sliding discharge gate according to claim 1, characterisedby the fact that, for moving the slidable intermediate plate, there isprovided a double-acting ram which is fixed to the lower support plateand whose stroke is equal to double the closing movement or openingmovement of the gate, suitable abutment means for limiting the stroke ofthe ram piston being provided in such a way that, at will, the pistoncan move between an intermediate position corresponding to the openposition of the gate, and one of its end positions, which end positionscorrespond to the closed position of the gate.
 3. Sliding discharge gateaccording to claim 1, characterised by the fact that the intermediateplate is moved by means of an actuating rod whose end is connected bymeans of a suitable connection piece to the ram piston rod, in which asuitable abutment means, preferably in the form of a fork, alternativelylimits in one direction or the other, the movement of said connectionpiece and thus of the piston from its intermediate position towards oneof its end positions.
 4. Sliding discharge gate according to claim 3,characterised by the fact that said connection piece is movable inside asuitable guide sleeve supported by the lower support plate, suitableapertures being provided in the walls of said guide sleeve for insertingsaid abutment fork on one side or the other of the intermediate positionof said connection piece.
 5. Sliding discharge gate according to claim1, characterised by the fact that, for the height regulation of theposition of the lower support plate, two swingable angle pieces areprovided, mounted on pivots fixed to the upper fixed plate, which anglepieces have wedge means for the height adjustment of the position of thelower support plate, in which said wedge means are provided, on eachside of the gate, a pair of lower, symmetrically-disposed wedges withtheir surfaces inclined in opposite senses, controlled mutually toapproach one another and move away from one another by means of a singleadjustment screw which is threaded right-handed in its portionassociated with the first wedge and left-handed in its portionassociated with the second wedge; in which above this pair of lowerwedge rest a single upper wedge provided all the same with two lowersurfaces which are inclined in opposite sense.
 6. Sliding discharge gateaccording to claim 1, characterised by the fact that the refractorybrick which is fixed to the slidable lower plate has two pouringapertures which are symmetrically positioned relative to itslongitudinal direction in such a way as to provide three locations forpositioning the gate, of which two are end, open positions of the gateand one is an intermediate, closed position of the same.